select(String,String,String) -- select and reformat substrings matching a regular expression

Synopsis

• Function: select

• Usage:

  select(re, replacement, str)

  select(re, str)

• Inputs:
  • re, a string, a regular expression describing a pattern
  • replacement, a string, following the formatting syntax
  • str, a string, a subject string to be searched
• Optional inputs:
  • POSIX => a Boolean value, default value false, if true, interpret the re using the POSIX Extended flavor, otherwise the Perl flavor
• Outputs:
  • a list, of mutually exclusive substrings of str matching the pattern re; if replacement is given, the matching substrings are formatted based on it.

Description

i1 : select("[[:alpha:]]+", "Dog, cat, and deer.")

o1 = {Dog, cat, and, deer}

o1 : List

i2 : select("^.*$", "ABC\nDEF\r\nGHI")

o2 = {ABC, DEF, GHI}

o2 : List

i3 : select("([a-zA-Z]+);", "$1", "Dog; cat, deer;")

o3 = {Dog, deer}

o3 : List

i4 : select("([a-zA-Z]+);", "\\L$1", "Dog; cat, deer;")

o4 = {dog, deer}

o4 : List

i5 : s = "catfish cats dogs";

i6 : select("cat(?!fish)s?", s)

o6 = {cats}

o6 : List

i7 : select("\\w+(?=s\\b)", s)

o7 = {cat, dog}

o7 : List

i8 : s = "goldfish swordfish catfish catdog";

i9 : select("\\w+(?=fish)", s)

o9 = {gold, sword, cat}

o9 : List

i10 : select("(?<=cat)\\w+", s)

o10 = {fish, dog}

o10 : List

See also

• regular expressions -- syntax for regular expressions
• strings and nets -- an overview of strings and nets in Macaulay2
• regex -- evaluate a regular expression search
• separate -- split a string into substrings using a regular expression
• replace(String,String,String) -- replace substrings matching a regular expression